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Biomedical subjects

C Andree

Publications and source records attributed to C Andree.

At least 19 recordsLinked to original sources
PubMed2001

Tissue engineering in plastic reconstructive surgery.

Tissue engineering (TE) is a new interdisciplinary field of applied research combining engineering and biosciences together with clinical application, mainly in surgical specialities, to develop living substitutes for tissues and organs. Tissue engineering approaches can be categorized into substitutive approaches, where the aim is the ex vivo construction of a living tissue or organ similar to a transplant, vs. histioconductive or histioinductive concepts in vivo. The main successful approaches in developing tissue substitutes to date have been progresses in the understanding of cell-cell interactions, the selection of appropriate matrices (cell-matrix interaction) and chemical signalling (cytokines, growth factors) for stimulation of cell proliferation and migration within a tissue-engineered construct. So far virtually all mammalian cells can be cultured under specific culture conditions and in tissue specific matrices. Future progress in cell biology may permit the use of pluripotent stem cells for TE. The blueprint for tissue differentiation is the genome: for this it is reasonable to combine tissue engineering with gene therapy. The key to the progress of tissue engineering is an understanding between basic scientists, biochemical engineers, clinicians, and industry.

Animals↗
PubMed2001

[Minimally invasive surgical therapy of gynecomastia: liposuction and exeresis technique].

INTRODUCTION: A number of techniques are available for the correction of gynecomastia. Nonscarring sparing methods are preferred, and the minimally invasive technique is to use liposuction for the gland and the fatty tissue exclusively. In this retrospective study we present our experience with a combination of liposuction and subsequent resection of the remaining gland. METHODS: Sixty-two patients (112 breasts) were surgically treated for gynecomastia from January 1996 and September 2000. From 1996 to 1997 all patients suffering from gynecomastia grade Simon I-II were treated by the method described by Rosenberg and Stark, which is exclusively suction of the fatty and glandular tissue. In a retrospective chart study a high recurrence rate was found in these patients. Subsequently we changed our technique to liposuction of the fatty tissue followed by sharp excision of the glandular tissue through the incision made for the liposuction cannula in the submammary fold. RESULTS: Suction alone was not sufficient to remove the glandular tissue; the rate of recurrence after suction was 35%. When sharp resection of the glandular tissue was carried out after the liposuction the recurrence rate dropped to under 10%. In total our complication rate was 50% including minor sequelae. The most frequent complication was unacceptable scarring of the nipple-areola complex. Hypesthesia of the nipple-areola occurred in 13.4% of the patients. CONCLUSION: The combination of liposuction and resection of the glandular tissue is a minimally invasive correction that can be used in all cases of gynecomastia grade Simon I-II.

Adult↗
PubMed2001

Management of hypovascularized wounds not responding to conventional therapy by means of free muscle transplantation.

BACKGROUND: Chronic ulceration as a complication of arteriosclerotic disease, venous congestion or diabetes mellitus is still a serious clinical problem, resulting in immobilization, extended hospitalization and cost-intensive treatment. Other than standard conservative treatment protocols or early amputation, microsurgical free transfer of well vascularized muscle tissue onto chronic wounds can induce angiogenesis and improve wound healing even in the hypovascularized wound. PATIENTS: From 1993-1999 we treated 12 patients (mean age: 46 years) with vascular ulcers of the lower extremity with free muscle or fasciocutaneous tissue transfer. RESULTS: The average hospitalization was 51.4 days. The perioperative mortality was zero. In one patient with factor V deficiency a partial flap necrosis occurred. Two revisions of the micro anastomoses had to be performed. Two seromas occurred at the donor site. No secondary flap loss was observed. Extremity or stump length preservation was achieved in all cases. CONCLUSIONS: Optimal postoperative treatment with physiotherapy and orthopaedic shoe support is important. If all these factors are present and if the patient is highly motivated a reintegration into normal life can be achieved.

Adult↗
PubMed2001

[Reconstruction of abdominal-wall midline defects--The Abdominal-Wall Components Separation].

AIM OF THE STUDY: The recurrence rate of midline defects like incisional hernias is high. Alloplastic material in sublay or onlay technique is often be used if the suture tension is to high for a primary closure. Free or pedicled musculocutaneous flaps transfer denervated muscle and lack dynamic resistance against the intraabdominal pressure. The separation of the lateral abdominal wall achieves autogenous, dynamic material for a tension free closure in small and moderate midline defects. METHODS: In 1990 Ramirez described a technique, which separates parts of the lateral abdominal wall and advances it towards the midline. The innervation and blood supply of the advanced part is maintained. With this technique it is possible to close defects tension free with dynamic abdominal wall. 9 patients were treated with this technique and followed up. RESULTS: Midline defects up to 16 cm at the waistline could be closed without tension. There were no major complications (one small delayed wound healing). There were no recurrences in a follow up time of 14.2 months. CONCLUSION: The separation of parts of the lateral abdominal wall can achieve tension free closure of e.g. incisional hernias of small and moderate size. The advancement of the medial component provides well innervated muscle for dynamic resistance against the abdominal pressure.

Adult↗
PubMed2001

Plasmid gene delivery to human keratinocytes through a fibrin-mediated transfection system.

We have developed a matrix-mediated transfection system to deliver plasmids to human keratinocytes. The matrix is a soluble, self-hardening fibrin matrix (Tissucol), Baxter) that has been used clinically. Recently it has been shown that full thickness burn wounds can be successfully treated with a keratinocyte fibrin glue suspension. Further, it has been demonstrated that hEGF transfected cells accelerate wound healing. In this study, we inoculated the matrix with the hEGF expression plasmid and resuspended the matrix with either cultured or noncultured human keratinocytes. We obtained successful transfection rates of these cells (up to a 100-fold increase compared to controls containing no EGF expression plasmid) in vitro. After transplantation to full thickness wounds on athymic mice we were able to show a 180-fold increase in EGF concentration compared to controls, which persisted over the entire 7-day monitored period, decreasing from 180 to 20 pg/mL at day seven. This unique approach indicates the possible utility to combine a matrix for cell transplantation with a transfection system to release therapeutic proteins in vitro and in vivo.

Animals↗
PubMed2001

Basement membrane formation during wound healing is dependent on epidermal transplants.

The purpose of the study was to compare directly the effect of healing and the formation of the basement membrane during wound healing from two autologous primary keratinocyte cultures in the liquid environment in full-thickness wounds in pigs. Wounds were either transplanted with cultured epidermal autografts (n = 26) or autologous keratinocyte suspensions (n = 24) or treated with saline alone (n = 40) and covered with a chamber. All wounds transplanted with cultured epidermal autografts and keratinocyte cell suspensions had positive "take" after transplantation. Healing times were significantly shorter for wounds treated with either cultured epidermal autografts or keratinocyte suspensions (p = 0.0001) compared with saline-treated wounds but were not different from each other (p = 0.1835). There were no differences in cytokeratin and laminin expression; however, staining with monoclonal antibody against collagen type VII showed a lower signal for cultured epidermal autografts only on days 8 and 16 compared with keratinocyte suspensions. Electron microscope evaluation showed a higher incidence of anchoring fibrils and a more mature dermal-epidermal junction in wounds treated with keratinocyte cell suspensions at day 8. These findings may be due to the single, noncontact-inhibited cells and the early formation of an in vivo neodermis to the wet wound environment. These data suggest that wounds transplanted with autologous keratinocyte suspensions in a wet environment may be an alternative method in the treatment of wounds.

Animals↗
PubMed2000

[Cell transplantation in surgery--reality and prospects for tissue engineering].

Traditionally surgical repair of tissue defects and loss or failure of function has relied on mechanical means, medical (drug) treatment, autologous and allogenic transplantation, and alloplastic/synthetic devices. Tissue engineering represents a new interdisciplinary field of applied research combining engineering and biosciences together with clinical application (mainly in surgical specialities) to develop living substitutes for tissues and organs. The understanding of cell-cell interactions and chemical signalling (growth factors) and the selection of appropriate matrices (cell-matrix interaction) is the key for success. Gene therapy represents the logical combination with tissue engineering on the molecular biology level. Application of cultivated skin and cartilage has already become reality, engineering of vascularized, more complex organs remains a challenge for this century.

Cells, Cultured↗
PubMed2000

[Gene therapy perspectives in modulation of wound healing].

A variety of reasons can afflict wound healing. Current research is focussed on the acceleration of wound healing by stimulating molecular processes. Gene therapy may offer completely new ways to treat chronic wounds. Possible advantages of gene therapeutic modulation of wound healing might be a long term efficiency, systemic or local regulation of gene expression and low side-effects. Current goals comprise the improvement of transfection efficiency and specificity. In vivo applications are therefore focussed on optimized inducible or even cell-type specific promotors, as well as on improved local application techniques. Studies from our laboratory demonstrate the possibility to combine modern cell culture techniques with different types of gene transfer. This enables the simultaneous grafting of manipulated cells to the wound with the continuous delivery of specific proteins of interest. Experimentally, this lead to accelerated closure of partial and full thickness animal wounds. Clinically, gene therapy for the treatment of chronic wounds seems to be a realistic goal within the next years and might be applicable for a variety of novel indications.

Animals↗
PubMed1999

Cultured epidermal keratinocytes on a microspherical transport system are feasible to reconstitute the epidermis in full-thickness wounds.

Research efforts to modify cultured autologous skin transplants for large full-thickness burn wounds and in chronic ulcers have shifted from multilayered differentiated grafts ("sheet" grafts) toward smaller units of basal undifferentiated single cell suspensions in a transport medium and subconfluently covered static carriers. It has been shown that wounds transplanted with single cell suspensions reconstitute the epidermis. However, this technique requires the detachment of the keratinocytes from the culture flasks by enzymatic digestion-digestion that might alter the anchoring proteins of the cells. A new approach might be to circumvent the enzymatic digestion to harvest the keratinocytes. This study reports a technique to culture epidermal cells on spherical microcarriers as a suspension culture and transport vehicle. The spherical microcarrier consists of a 100-microm-diameter collagen-coated dextran carrier (Cytodex 3 Pharmacia) and has been used previously for enzyme production commercially. With this new approach, we seeded the human keratinocytes in a spinner-like system onto microspheres and transplanted these micrografts onto full-thickness wounds on the back of nude mice. After 14 days, we showed a reconstituted epithelium that was multilayered and keratinized compared to control wounds. We believe that this is the first step of a new approach to increase the cell yield for seeding without altering the anchoring proteins by enzymatic steps, leading to a superior transplantation method for keratinocytes.

Adult↗
PubMed1999

[Free microsurgical flap-plasty in reconstructive therapy of diabetic foot ulcer].

The diabetic foot ulcer is a significant clinical problem often resulting in frustranous conservative treatment or early amputation. In certain cases transfer of well vascularized tissue can improve wound healing and lead to a length-spearing therapy. In this study the concept of microsurgical tissue transfer in the treatment of diabetic foot ulcers is introduced. Following a radical debridement and, if necessary a atypical length-spearing amputation the wound is covered by a free transplanted muscle flap followed by a split-thickness skin graft. In six patients treated with this procedure the extremity could be saved. The perioperative mortality was 0%, average hospitalization was 47.6 days. One flap was lost, two vascular revision were necessary. Several necrectomies and skin grafts were performed and one donor side seroma was drained. One hernia was observed after free rectus abdominus transfer. Compared to conservative treatment or amputation this concept leads to a length-spearing therapy and can increase success rates of rehabilitation and quality of life.

Amputation, Surgical↗
PubMed1999

[Keratinocyte transplantation and tissue engineering. New approaches in treatment of chronic wounds].

Cultured keratinocytes have been used for the treatment of extensive burns since disease lethality is reduced. Consequently, the treatment of chronic wounds with keratinocytes may be promising. Cell culture technology allows to expand keratinocytes up to 6000-fold in vitro after taking a single biopsy from patient. Today the transplantation of these in vitro cultured keratinocytes in different modifications is an established clinical treatment regimen for therapy of extensive wounds. For example, keratinocyte-fibrin-glue-suspensions, mainly consisting of proliferative epidermal basal cells, were used for the treatment of burns in experimental and clinical settings to bypass the disadvantages of conventional sheet grafts. Other approaches in tissue engineering for wound healing aim at the (epi-)dermal repair by the combination of allodermis and biomaterials, i.e. collagen-sponges and microspheres. Due to most recent efforts in keratinocyte culture techniques, developments in tissue engineering, research for novel biomaterials and gene therapy, therapy of chronic wounds may prove to be more efficient. Furthermore, from the socio-economical point of view, overall costs for treatment of chronic wounds could be reduced.

Cell Division↗
PubMed1998

In vivo gene transfer to skin and wound by microseeding.

BACKGROUND: Gene transfer to skin has many potential applications but lacks a safe, practical delivery method. This report presents a new technique, microseeding, for in vivo gene transfer to skin and wounds and for DNA-mediated vaccination. The plasmid DNA solution was delivered directly to the target cells of the skin by a set of oscillating solid microneedles driven by a modified tattooing device. MATERIALS AND METHODS: Skin and partial-thickness excisional wounds in pigs were microseeded with either hEGF expression plasmid or beta-galactosidase expression plasmid. Human EGF was also delivered by single injection or particle bombardment. hEGF expression in wound fluid and in target tissue was determined by ELISA with anti-hEGF-specific antibodies. Additionally, weanling pigs were microseeded with a hemagglutinin of swine influenza virus expression plasmid and production of anti-HA-specific antibodies was determined by blocking ELISA. RESULTS: hEGF expression in microseeded partial thickness wounds (5664 pg/site) and skin sites (969 pg/site) peaked 2 days after transfection being four- to seven-fold higher than gene transfer by a single intradermal injection and two- to three-fold higher than particle-mediated gene transfer. The beta-galactosidase-expressing cells were detected in dermis and epidermis. Pigs microseeded with HA expression plasmid were protected from infection by the Swine influenza virus. CONCLUSIONS: These results demonstrate that microseeding is a simple and effective method for in vivo gene transfer to skin and wounds and is more efficient than single injection and particle-mediated gene transfer.

Animals↗
PubMed1997

Growth factors in the repair of partial thickness porcine skin wounds.

In 28 porcine partial thickness excisional wounds, the presence of several growth factors was first studied by enzyme-linked immunoadsorbent assay on wound fluid collected in sealed wound chambers. Basic fibroblast growth factor (bFGF) peaked on day 1 at 31.4 pg/ml; platelet derived growth factor (PDGF)-AB on day 3 reached 45.2 pg/ml, and transforming growth factor-beta (TGF-beta) on day 7 was 726.1 pg/ml. The same chamber system was used in 48 partial thickness excisional wounds for delivery of nanogram doses of bFGF, PDGF-AB, insulin-like growth factor (IGF)-1, epidermal growth factor (EGF), and cholera toxin. PDGF and EGF accelerated healing (1.1 days and 0.3 days, respectively), whereas bFGF and IGF-1 had no effect. Cholera toxin retarded healing by 1.9 days. Furthermore, in 100 excisional wounds EGF in the concentration range of 10 to 1,000 ng/ml had the same stimulating effect on healing. EGF at 10,000 ng/ml significantly delayed healing. The wound chamber model is useful for detecting of endogenous growth factors as well as for delivering exogenous factors.

Animals↗
PubMed1996

Treatment of chronic, nonhealing abdominal wound in a liquid environment.

A 66-year-old woman with an abdominal wound caused by infected synthetic mesh had failed to heal in spite of many surgical attempts to close the wound. A sealed transparent vinyl chamber was glued to the periphery of the wound and antibiotics in high concentrations (up to 2,500 times the minimum inhibitory concentration) were delivered through the chamber. The wound fluid in the chamber was used for analysis of microbial activity, concentration of residual antibiotics, and growth factor activity. After 10 weeks of treatment, the wound was closed and has not recurred in 24 months.

Abdominal Injuries↗
PubMed1996

Short contact 70% glycolic acid peels as a treatment for photodamaged skin. A pilot study.

BACKGROUND: Glycolic acid has been one of the more commonly used alpha hydroxy acids for the treatment of photodamaged skin. Its value as a quick "skin refreshing" peeling agent has been widely touted. This type of peel differs from a conventional therapeutic peel (eg, phenol, trichloroacetic acid, or a longer time exposure alpha hydroxy acid peel) in that there is little skin reaction and patients can go about their daily routine without concern. OBJECTIVE: To assess the potential value of glycolic acid-based refresher peels as a cosmetic procedure. METHODS: Twelve healthy subjects with at least a moderate degree of photodamage were treated with monthly serial 70% glycolic acid peels over a period of 4 months. In addition to the "peels," six subjects were randomized to a 10% glycolic acid-based moisturizer twice daily. Patients were evaluated monthly and graded on a clinical scale using objective measures. RESULTS: No conclusive differences were noted on histologic evaluation. Ninety percent (9/10) of patients felt that overall they noticed significant improvement, however, there was no distinction between the two treatment options. The improvement in fine wrinkling and pigmentation was primarily seen in the patients who additionally received 10% glycolic emollient twice daily. CONCLUSION: In this limited pilot study, no specific benefit could be assigned to the concomitant use of monthly glycolic acid refresher "peels" in the treatment of photodamaged skin.

Adult↗
PubMed1995

Dry, moist, and wet skin wound repair.

Effects of wet (saline in a vinyl chamber), moist (hydrocolloid dressing), and dry (sterile gauze dressing) environments on wound repair were studied in a porcine partial-thickness wound model. Chambers were exchanged and refilled daily with normal saline containing penicillin G (100 U/ml) and streptomycin (100 micrograms/ml). Hydrocolloid and gauze dressings were kept in place until biopsy of the wound site. Wounds in wet, moist, and dry environments were completely epithelialized on days 6, 7, and 8, respectively. Thickness of the epidermis in wet, moist, and dry wounds was 204 +/- 23, 141 +/- 12, and 129 +/- 18 (mean +/- SEM), respectively. Moist wounds had more subepidermal inflammatory cells than wet wounds. In comparison to dry wounds, the moist or the wet healing environment resulted in less necrosis and faster and better quality of healing in the formation of the newly regenerated epidermis.

Animals↗
PubMed1995

Gene transfer.

The principles and techniques of gene transfer are presented. Common concepts are defined, and the frequently used transfer vectors are described herein. Several gene transfer applications are discussed briefly. Areas of particular interest to the plastic surgeon such as gene transfer to skin and wounds are included.

Gene Expression↗